Modern society has an ever-growing desire for robust, lightweight and versatile portable electronic devices. One growing area of consideration for such products is the development of devices in a flexible form factor that can operate without deterioration in performance. Durability and robustness are desirable properties that contribute to the commercial success of flexible displays and photovoltaics. Beyond flexibility, printability and functionality of the components, other desirable properties for the thermally stable materials are resistance to adverse environmental conditions such as oxygen and moisture. Some of the desirable performance metrics are low permeability to water and oxygen (10−6 g/m2/day for H2O and 10−5 g/m2/day for O2) and high thermal stability (ideally up to 300° C.).
Substrates and barriers such as glass and metal provide excellent barriers to oxygen and moisture, but may result in rigid devices that do not satisfy applications demanding flexible devices. On the other hand, plastic substrates and transparent flexible encapsulation barriers may be used, but these often offer little protection to oxygen and water, resulting in devices that may rapidly degrade from environmental conditions.
An electrically insulating, atomically thin sheet of hexagonal boron nitride (h-BN) may provide an ideal barrier for flexible electronics, however because h-BN has a low chemical reactivity, functionalization of h-BN may be difficult. Chemical functionalization of h-BN, has resulted in breakage of the ring structures, thereby creating holes in the structure, resulting in a loss of strength and permeability. Therefore, there remains a need for flexible barrier layer materials and flexible substrate layer materials that meet the required permeability parameters for oxygen and water, while also being compatible with high-temperature processing or integrated functionality.